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Kosuke Morikawa

Publications and source records attributed to Kosuke Morikawa.

41 records · Page 3Linked to original sources
PubMed2002

Crystal structure of the RuvA-RuvB complex: a structural basis for the Holliday junction migrating motor machinery.

We present the X-ray structure of the RuvA-RuvB complex, which plays a crucial role in ATP-dependent branch migration. Two RuvA tetramers form the symmetric and closed octameric shell, where four RuvA domain IIIs spring out in the two opposite directions to be individually caught by a single RuvB. The binding of domain III deforms the protruding beta hairpin in the N-terminal domain of RuvB and thereby appears to induce a functional and less symmetric RuvB hexameric ring. The model of the RuvA-RuvB junction DNA ternary complex, constructed by fitting the X-ray structure into the averaged electron microscopic images of the RuvA-RuvB junction, appears to be more compatible with the branch migration mode of a fixed RuvA-RuvB interaction than with a rotational interaction mode.

Adenosine Triphosphatases↗
PubMed2002

Physical interaction between proliferating cell nuclear antigen and replication factor C from Pyrococcus furiosus.

BACKGROUND: Proliferating cell nuclear antigen (PCNA), which is recognized as a DNA polymerase processivity factor, has direct interactions with various proteins involved in the important genetic information processes in Eukarya. We determined the crystal structure of PCNA from the hyperthermophilic archaeon, Pyrococcus furiosus (PfuPCNA) at 2.1 A resolution, and found that the toroidal ring-shaped structure, which consists of homotrimeric molecules, is highly conserved between the Eukarya and Archaea. This allowed us to examine its interaction with the loading factor at the atomic level. RESULTS: The replication factor C (RFC) is known as the loading factor of PCNA on to the DNA strand. P. furiosus RFC (PfuRFC) has a PCNA binding motif (PIP-box) at the C-terminus of the large subunit (RFCL). An 11 residue-peptide containing a PIP-box sequence of RFCL inhibited the PCNA-dependent primer extension ability of P. furiosus PolI in a concentration-dependent manner. To understand the molecular interaction mechanism of PCNA with PCNA binding proteins, we solved the crystal structure of PfuPCNA complexed with the PIP-box peptide. The interaction mode of the two molecules is remarkably similar to that of human PCNA and a peptide containing the PIP-box of p21(WAF1/CIP1). Moreover, the PIP-box binding may have some effect on the stability of the ring structure of PfuPCNA by some domain shift. CONCLUSIONS: Our structural analysis on PfuPCNA suggests that the interaction mode of the PIP-box with PCNA is generally conserved among the PCNA interacting proteins and that the functional meaning of the interaction via the PIP-box possibly depends on each protein. A movement of the C-terminal region of the PCNA monomer by PIP-box binding may cause the PCNA ring to be more rigid, suitable for its functions.

Amino Acid Sequence↗
PubMed2002

[Ligand recognition mechanism of G-CSF receptor and metabotropic glutamate receptor].

A three-dimensional view of ligand-receptor recognition at the atomic level is crucial to understand the molecular mechanism of receptor activation. This review describes the structure-function relationships of two receptors important for pharmaceutical science. Granulocyte colony-stimulating factor (G-CSF) is the principal growth factor regulating the maturation, proliferation, and differentiation of the precursor cells of neutrophilic granulocytes. We have determined the crystal structure of G-CSF complexed to the BN-BC domains, the principal ligand binding region of the G-CSF receptor. In a novel oligomerization scheme, the two receptor domains complex in a 2:2 ratio to the ligand, with a noncrystallographic pseudo-two-fold axis through primarily the interdomain region and secondarily the BC domain. This first structural view of a gp130-type receptor-ligand complex presents a new molecular basis for cytokine-receptor recognition. The metabotropic glutamate receptors (mGluRs) are key receptors in the modulation of excitatory synaptic transmission in the central nervous system. Three different crystal structures of the extracellular ligand-binding region (LBR) of mGluR1 have been determined, in a complex with glutamate and in two unliganded forms. They all showed disulfide-linked homo-dimers, of which the "active" and "resting" conformations are modulated through the novel dimeric interface by a packed alpha-helical structure. The bilobed protomer architectures flexibly change their domain arrangements between an "open" or "closed" conformation. Glutamate binding stabilizes both the "active" dimer and "closed" protomer in dynamic equilibrium. Four domain movements within the dimer affect the separation of the transmembrane and intracellular regions and thereby activate the receptor.

Animals↗